Adobe PHOTOSHOP 5.0 User Manual page 131

Once again, although you can use the Levels
command, Curves offers the most precise control
over pixel distribution within a channel. The
commands Hue/Saturation, Replace Color, and
Selective Color offer additional control over
specific color components and attributes. For
examples of corrections of specific color imbal-
ances, see "Correcting The Color Plates" on
page 232.
Adjusting color balance
Every color adjustment affects the overall color
balance in your image. You have numerous ways to
achieve similar effects, so determining which
adjustment is appropriate depends on the image
and on the desired effect.
It helps to keep a diagram of the color wheel on
hand if you're new to adjusting color components.
You can use the color wheel to predict how a
change in one color component affects other
colors and also how changes translate between
RGB and CMYK color models. For example, you
can decrease the amount of any color in an image
by increasing the amount of its opposite on the
color wheel—and vice versa. Similarly, you can
increase and decrease a color by adjusting the two
adjacent colors on the wheel, or even by adjusting
the two colors adjacent to its opposite.
For a color illustration of the color wheel,
see figure 6-3 on page 225.
For example, in a CMYK image you can decrease
magenta either by decreasing the amount of
magenta or its proportion (by adding cyan and
yellow). You can even combine these two correc-
tions, minimizing their effect on overall lightness.
In an RGB image, you can decrease magenta by
removing red and blue or by adding green. All of
these adjustments result in an overall color balance
containing less magenta.
For a color illustration of correcting color
plates with the Curves command, see the
sidebar on page 232.
Using the Color Balance command
The Color Balance command lets you change the
mixture of colors in a color image. Like the
Brightness/Contrast command, this tool provides
generalized color correction. For precise control
over individual color components, use Levels,
Curves, or one of the specialized color correction
tools: Hue/Saturation, Replace Color, or Selective
Color.
Note: You can also change the mixture of colors with
the Channel Mixer command. (See "Mixing
channels" on page 243.)
To adjust the levels of a particular color in
an image:
1 Open the Color Balance dialog box, as described
in "Using color adjustment commands" on
page 105.
Note: You must be viewing the composite channel to
use the Color Balance command. (See "Using the
Channels palette" on page 240.)
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